Preventive maintenance is the key when considering wheel alignments. Keeping your wheels aligned will save you tread ware, which saves you money. You will get the best performance and wear from your tires when you routinely align your wheels. Poor alignment is a result of the suspension and steering systems being out of adjustment. This usually results in abnormal treadware. If you notice unusual wear on your tires, check the inflation pressure of your tires, and have your alignment checked.
There are three types of wheel alignments: front-end, thrust angle and four-wheel alignment. The most complete method of alignment is four-wheel alignment. Four-wheel alignment combines front-end with thrust angle and includes a check on the rear wheels as well. Front-end alignments check only the front tires. Thrust angle checks that the wheels are "squared" to each other, preventing your car from going sideways on the road.
Caster, camber and toe are the measurements that must be checked during an alignment. High-speed stability and low speed steering efforts are balanced by caster settings. If you increase your positive caster, you will increase low speed steering efforts and improve high-speed stability.
The amount the tire is tilted away from the vertical is camber. When set properly, camber will allow the tire to function optimally without putting too much of its force on the inner edge while moving in a straight line. Tire wear and handling are affected by camber. Negative camber is when the top of the tire leans toward the center of the vehicle. Decreasing negative camber gives very even wear, but will normally reduce cornering abilities. A tire has positive camber when the top of the tire is leaned outward from the center of the vehicle. The camber angle should be adjusted so that the tire is vertical under cornering load.
Toe is the difference in distance between the front and the rear of the tires. Toe-out is the term used to describe the event that the distance is greater between the front than in the rear. Toe-in, or pigeon-toed, describes the distance between the tires is less in the front.